Georg wilhelm kraft



(No Model.) r

G. W. KRAFT. FLEXIBLE RULER.

Patented Jan. 24, 1893;

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GEORG IVILI'IELM KRAFT, OF DRESDEN, GERMAN Y, ASSIGNOR TO LINGNER d:KRAFT, OF SAME PLACE.

FLEXlBLE RULER.

3PECIFICATION forming part of Letters Patent No. 490,390, dated January24, 1893.

Application filed August 6, 1892- Serial No. 442,301. (No model.)Patented in France July 17, 1890, No. 207,080; in Germany February 17,1891,1lo. 58,6543 in England June 8, 1891,1To. 9,697, and inAustria-Hungary February 25, 1892.

To all whom it may concern: Similar letters of reference designate comeBeithnown that LGEORG IVILHELM KRAFT, spending parts in all the figures.

of Dresden, in the Kingdom of Saxony, in the The ruler shown in Fig. 1simply consists German Empire, have invented certain new of two elasticplates of suitable length and 5 and useful Improvements in FlexibleRulers, width, one of the plates a being of steel of of which thefollowing is a specification, and convenient minimum thickness, theother which has been in part patented in France plate Z) being of a softmaterial such as soft by brevet No. 207,080, dated July 17, 1890;indiarubber, the two plates being secured toin Germany by Patent No.58,654, dated Febgether by rivets or any other suitable means,

10 ruary 17, 1891; in Great Britain by Patent the plate of soft materialbeing of less'width No. 9,697, dated June 8, 1891, and in Austriathanthe steel plate to which it is attached for Hungary by Privilegium, Tom.42, Fol. 511, allowing at least one edge of the steel plate Tom. 26,Fol. -l17, dated February 25, 1892. to protrude or project to form apermanent In drawing lines with an ordinary ruler as edge for ruling,but the said plate of soft ma- 15 hitherto in use there is adifficultyindrawing terial being of such thickness that a proper the lines straightif the object ruled does not distance is established between the paperto present a level surface as is the case for exambe ruled and theruling edge of the steel plate, pleinlargebusinessledgers and otherlargeso which latter of course in using the ruler,lies count books on thecurved surfaces of the uppermost.

20 sheets of which the ruler cannot be pressed In the example shown inFigs. 2, 3 and 5,

down evenly. The production of a flexible the ruler consists of twoelastic plates to a, of ruler has met with these difficulties, viz: thatsuitable length and width, both plates being when constructed of hardmaterial the ruler made of steel of convenient minimum thickhad, inorder to be really flexible, to be made ness suitable for the purpose.These two elas- 2 5 too thin whereby the drawing edge of the ruler ticplates are connected together in such mancomes too near to the papercausing blotting ner that they lie with their flat sides parallel on thepaper; and when made of a soft and with each other and if desired atsuch a dis.- fiexible material, such for example as indiatance apartfrom each other as to constitute rubber, the soft edge of such materialdoes the thickness of an ordinary ruler, the con- 0 not offer resistanceenough against the pen. nection being such that the parallelism is Theobject of the present invention is to always kept up while the twoelastic plates construct a ruler which combines the followmay be shiftedindependently of each other ing qualities and advantages (first) havinga in the lengthwise direction. I preserve the hard or resisting drawingedge, (second) being full elasticity of each plate and thereby of the 35 high enough to prevent the necessary disruler composed of such plates.I prefer to tance between the paper and the drawing make the said platesa a of steel but reserve edge and (third) being so flexible that iteasily to myself the right of using any material yields to adapt itselfto curved surfaces with which in very thin plates combines the necestheslightest pressure. The ruler constructed sary flexibility, hardness andresistance. The

40 according to thisinvention possesses all these lower plate a isprovided with studs or prodesirable qualities and advantages. jections dat its upper surface, said studs end- 0 Figure 1 is a side view of oneexample of a ing in a round head and having an annular ruler embodyingmy invention. Fig. 2 is a recess f below the head. The upper plate aside view of another example of my invention. is provided with longslots 0, each slot having 5 Fig. 3 is a top view corresponding with Fig.at one end a widened opening for the head of 2. Fig. i is a partiallongitudinal section in the studs (Z to enter, whereas the slots are of5 the line w to of Fig. 3. Fig. 5 is a perspective smaller dimensions inthe remainder of their view showing the ruler in use on an accountlength to allow the annularly recessed porbook. tionsfof the studs toenter into them. In

the middle or near the middle of the lower plate CL and on its uppersurface a nut z'is affixed, the upper plate a at the corresponding placebeing provided with a hole for the screw 9, with a milled head to enterthe nut and to combine the two plates a and a rigidly at or near theirmiddle part while leaving them free to move independently of each otherwhen in use to accommodate the ruler to curved surfaces which are to beruled. Iprefer to make theglower plate a. of less width as indicated indotted lines in Fig. 3, so as to prevent the said plate from beingtouched by the ink of the pen, thus imitating the hollow recess usual inwooden rulers.

In using the ruler the protruding edge of the upper plate a serves asthe permanent drawing edge for the pen to rest against, whereas thelower plate a rests on the paper to be ruled and preserves or protectsthe paper from being soiled or blotted by the ink, which in the act ofdrawing adheres to the edge of the upper plate and dries up between thetwo plates. The space or room between the two plates may, if desired, befilled up with asoft substance such as paper which,in long strips of thewidth of the lower plate or of less width, is provided with elongatedholes to pass over the studs (Z, such strips preserving the paral lelismbetween the two plates but being capable of shifting longitudinallyindependently of each other. If an absorbent material is used to fill upthe space between the plates, such material will take up the inkadhering to the drawing edge of the upper plate.

Such an elastic and flexible ruler may be composed of more than twoplates, connected together and being capable of shifting independentlyin lengthwise direction the elasticity and flexibility however of suchruler being inferior to those composed of two plates only.

If the ruler is laid for use on asurface of a certain curvature, theruler will by the slightest pressure on the top plate accommodate itselfto the surface by bending so that it rests on all parts of the surfacein the line to be drawn, thus insuring a straight line withoutnecessitating the rocking of the ruler as is the case if the latter isstiff and rigid in all its parts. lVith niyimproved ruler the plates (1.and a, will always, even if bent, remain parallel, whereas the platesare capable of shifting independently of each other, to yield while theruler is bent.

I may connect the two plates to and a in any suitable manner such as bymeans of hinged parts arranged between the two plates at and a allowingthese two plates to shift independently of each other in lengthwisedirection, but maintaining all the while their parallelism. But I havefound the recessed studs in combination with the elongated slots to bepreferable, said construction afiording the possibility of easilydetaching the two plates by simplyunscrewin g the middle screw g andshifting the upper plate so as to allow the stud heads to escape throughthe holes provided for them.

I do not limit myself to the exact construction of the ruler asexplained above; I reserve to myself the right to vary the partsaccording to will, always maintaining in an elastic or flexible rulerthe parallelism of the upper and lower thin plates and their capabilityof lengthwise shifting independently from each other, therebyconstituting a ruler capable of yielding to the curved surface of theobject to be ruled and yet being of the sufiicient height or thicknessand resistance and oifering a stiff and rigid edge for the pen to restagainst in the act of ruling.

I may mention that instead of the studs with recesses under their head,rivets may be used which with their stems are fixed to the one platewhile the rivet heads pass through the holes of the other plate and thestems of the rivets slide in the elongated slots of this latter plate.

What I claim as my invention is:

1. A flexible ruler capable of adapting itself to different forms ofsurfaces to be ruled composed of two elastic plates combined together,the one being ametal plate, the other being a plate of soft and elasticmaterial, one edge of the metal plate forming the ruling edge while theother plate keeps the distance between the ruling edge and the paper tobe ruled, substantially as herein set forth.

2. A flexible ruler composed of two or more superposed elastic plates ofmetal or other material, of which one has a permanent ruling edge, and aconnection substantially as herein described between the said plateswhich permits the said plates to shift independently of each other inlengthwise direction when the ruler is in use to enable the ruler toadapt itself to curved surfaces, as herein set forth.

3. A flexible ruler composed of two or more flexible plates (0 and aprovided with studs or rivets d and with elongated slots 0 for the studsor rivets to enter into and to slide freely within, and a fasteningbetween said plates which secures them firmly together at one pointintheir length while permitting them to slide freely the one relatively tothe other throughout the rest of their length, substantially as hereindescribed.

at. In a flexible ruler, the combination of two elastic plates separatedfrom each other but connected together to shift lengthwise independentlyof each other and one of which has a permanent ruling edge, and aninterposed filling of flexible and soft material, substantially as andfor the purpose set forth.

In testimony that I claim the foregoing as my invention I have signedmyname in presence of two subscribing witnesses.

GEORG XVI LHELM KRAFT.

Witnesses:

FRANZ RIESKE, OURZ SOHAUFUSS.

ITO

